The present disclosure relates to a proximity sensor valve, and more particularly to a proximity sensor valve that mechanically prohibits fluid pressure from communicating with fold components, e.g. of a rotary-wing aircraft blade fold system, until the components are properly positioned.
Aircraft, particularly rotary-wing aircraft utilized for maritime flight operations, may be required to conduct operations from ships for extended periods of time. Shipboard space is generally at a premium, and the structural envelopes of aircraft may require a relatively significant allocation of such limited space. Furthermore, strategic and tactical considerations in the utilization of rotary-wing aircraft has led to a requirement for rotary-wing aircraft having main rotor assemblies that may be readily reconfigured for rapid deployment, routine transport, and/or stowage through reduction in structural envelope.
Several options are available to reduce the structural envelope of aircraft to facilitate rapid deployment, routine transport, stowage, and reduce the vulnerability thereof to environmental conditions. One option with rotary-wing aircraft is to design the main rotor assemblies thereof so that the main rotor blade assemblies fold relative to a main rotor hub assembly, and therefore, relative to the fuselage. A similar type approach is often taken with fixed wing aircraft. With this type of aircraft, all or a portion of the wing is typically folded with respect to the fuselage in order to reduce the overall envelope of the aircraft.
Various blade fold systems typically include pitch lock and hinge lock systems which often times react the loads of a folded blade with a retractable mechanical coupling. Verification of blade fold functionality often utilizes a combined hydraulic-electrical system in which blade fold position verification logic for the retractable mechanical couplings are related to the position of numerous electrical switches and sensors. Although effective, the presence of harsh environments, clearance issues, and vibration extremes may result in reduced reliability of the electrical sensors and switches over a period of time.